So why do we bother..? Both in fiction and reality we seem to set much store by rigidly behaving today just as we behaved yesterday. We have our pride and our principles and sometimes we adher to them even to the point of derision or death. It would seem mal-adaptive to have an intrinsic mechanism that drives us to become 'one' person, when a chameleon might prosper better. And yet such a trait seems pan-human.
What worth is being only one certain individual to the individual concerned..?
None at all that I can think of.
Then I remembered my friend, and die-hard drinking-buddy, who suddenly stopped drinking and went tee-total. And about how we aren't all that good friends anymore. And about another friend, who suddenly caught a very bad case of christianity, and about how we went from bosom buddies to erm, not-so bosom buddies almost overnight.
I think we grit our teeth and preserve a coherent and damn near constant self, not through any aesthetic drive to self-expression, nor even from some abstract existential drive to 'authenticity'.
I think we instinctively maintain our particular brand of 'selfhood' simply to preserve social trust. To make sure that the people with whom we deal on a day to day basis know we are X and not Y, A but not B, and therefore safely predictable enough for them to not fear what 'me' tomorrow may bring.
We fear the weirdo or the madman, not because of their (maybe) inhuman strength, nor for their (possible) penchant for eating people's faces - but simply because we cannot know with any degree of certainty what they will do next, or how they will react to what we do, however innocuous in our eyes. Will he shake my hand or break it..? So we freeze, or shoot, or run.
How would my wife love me if I awoke a new person every day..? How would my child dare aproach me if he could not be sure whether my proximity would bring a hug or a blow..? Would my neighbor loan me his mower if he couldn't be reasonably sure I'd give it back and not sell it, or scrap it, or wrap it round his head..?
The irony is then, much of this 'I' we set such store by, and go to such lengths to preserve, is not even for ourselves.
My 'I' is not for me, it is for you, it's always been for you.